Film inspecting apparatus



. Sept. 29, 1942.

Original Filed June 9, 1938 G. KEMNA FILM INSPECTING APPARATUS 4Sheets-Sheet l Sept. 29, 1942. GJKEMNA FILM INSPECTING APPARATUSOriginal Filed June 9, 1938 4 Sheets-Sheet 2 'axiavlmzm Sept. 29, 1942.KEMNA FILM INSPECTING APPARATUS 4 Sheets- Sheet 3 Original Filed June 9,1938 Patented Sept. 29, 1942 FILM INSPECTING APPARATUS Gustav Kemna,Babelsberg, Germany; vested in the Alien Property Custodian Originalapplication June 9, 1938, Serial No. 212,784. Divided and thisapplication June 19, 1939, Serial No. 279,975

6 Claims. (Cl. 8816.8)

The invention relates to film inspection machines or tables which areemployed for examining a picture film and its accompanying sound film,in order to ascertain whether the picture and sound are in synchronism,whether at any part thereis any technical or artistic objection to thepicture or sound reproduction, and generally to edit the film, the finalcutting of the sound film, and/or picture film being effected on thetable. I 7

An object of the invention is to construct and arrange the optical partof such apparatus in a novel manner whereby an improvement of theapparatus as a whole is achieved. Another object is to effect asubstantial simplification of the apparatus whereby its operation isgreatlyfacilitated andit is easier to manufacture and maintain. Anotherobject is to provide an apparatus of the class referred to in which allelectrical conductors and all mechanical and op tical connections aremore easily accessible than hitherto so that their'supervision isfacilitated. A Iurther object is the provision of means for readilyadapting the apparatus for inspecting a picture film with itsaccompanying sound film, regardless of whether the two films underexamination are both of standard (35 mm.) or

sub-standard size, or are diflerent sizes.

For ,a more detailed explanation of the invention, reference is made tothe accompanying drawings illustrating two embodiments by way ofexample. 7

In the drawings:

Fig. 1 is a plan view of one embodiment of the apparatus, detailsirrelevant to the invention being omitted;

Fig. 2 is a sectional view of the apparatus taken on the line 2-2 ofFig. l and drawn on a larger scale;

Fig. 3 illustrates schematically on a larger scale the optical part ofthe apparatus, the possible courses of the light rays being indicated inchain-dotted lines:

Fig. 4 illustrates another embodiment showing means for adaption todifierent film sizes;

Fig. 5 shows a detail of Fig.4 on larger scale; and Figs. 6, '1 and 8schematically illustrate the. manner in which the apparatus of Fig. 4 isutilized for various combinations of film sizes.

The general layoutor the apparatus top or operating table" as it will becalled herein for convenience can be seen from Fig. 1. The picture filmruns from the top left feed spool 29 spool 29, both films beingsynchronized by .being led together over' a synchronising sprocket 20.

From therethe picture film passes over the tensioning roller andconventionally-provided idler rollers, past a film gate at I, over amovable -roller 26 mechanically coupled to a manbetween the photocelland a slit projector 23 for exciting the cell in known manner. The

sound film then passes over a tensioning roller? carried by theadjustable tensioning lever 21, and

thence passes over an idler roller to a driven sprocket,- 22, which isadvantageously an eightframe sprocket. From there the sound film' iswound on the bottom right take-up spool 29a. A friction roller'illisprovided for moving the film by hand. 28 indicates a loudspeaker throughwhich is reproduced in known manner the sound recorded on the film.

Referring to Figs. 1 and 2, the optical part of the apparatus comprisesa matt screen 3 and hood 3' located to the front of the'operating table.and behind these a lamp house 13- containing a lamp l2, an eight-sidedprism it, an

- objective I! and lens system it. The eight-sided prism II is mountedon a vertical shaft and rotated by a worm drive it. On the same shaft ismounted a disc li which rotates with the prism 10 and is provided withslit diaphragms, arranged radially and so that they come verticallybelow the'lens system It, as shown more clearly in Fig. 3. Above thesystem IS, the deviating prism i5 is rigidly mounted on the operatingtable of the apparatus.

The operating table comprises depending. sides 8 forming a casing openat the bottom which is supported by an under-structurecomprising anupright frame I and platform 2, the operating table being hinged at, itsback to the platform 2 as at! so that it can be raised from'the front inthe direction of the arrow shown in Fig. 2.

The film feed'devices and the optical and other devices so far describedare mounted above and below the operating table and carried thereby ascan be seen from Figs. 1 and 2. The operating table casing also carriesthe necessary electrical equipment including an amplifier (not shown)for amplifying the output of the photocell 24 and and the sound filmfrom the bottom left feed passing it to the loudspeaker 28, adjustableresistance' or resistances I8 for controlling the intensity of the lampI2 and also if desired the ex- .citer lamp of the slit projector '23,all necessary conductors for electrically connecting the variouselectrical devices, and also the necessary control knobs or the like forregulating the lamps and the sound reproduction. Details of suchequipment are notshown since it is of conveninadvertent operation, thesurface of the operating table is preferably extended at the front P'soas to overhang the side& of the casing and advantageously also theplatform 2 is similarly extended, whereby the control knobs or the likeare contained in a channel or recess at the front of the operatingtable. Preferably, also, the electrical devices controlled by the saidknobs or the like are arranged as near-as possible to the front of thetable so that the electrical connections can be as short as possible.

The under-structure I, 2 carries a light tight box or chamber 5 which isfitted with an adjustable mirror 4 for projecting light onto' the mattviewing screen 3, the platform 2 being apertured to permit thenecessary" transmission of light. Adjustment of the'mirror 4 is effectedby means of the adjusting screws 6 and I.

In the preferred arrangement as illustrated, the optical system is builtinto the middle zone of the apparatus so that in the ideal case thecentre ray of light from the lamp I2 lies in .a vertical plane A-B Fig.1, throughout its passage from the lamp l2 to the viewing screen 3. Inpractice it is not necessary to' achieve exactly this ideal arrangementsince with an approximation the same advantages are obtained of a simpleand compact construction and conservation of light giving intenselyilluminated and sharp pictures free from color fringes.

In the preferred arrangement, the electrical equipment, as well as theoptical system, is built in the middle zone of the table so that allconnections are kept as short as possible with consequent simplificationin maintenance.

With the-exception of the mirror 4, all optical, mechanicalandelectrical parts of the apparatus are carried by the operating table,whethermounted on its surface or built within its casing. Simply bylifting the "operating table about the hinge 9, everything built intothe interior of this casing is rendered easily accessible so thatcleaning, inspection and general supervision of all the devices isfacilitated. The surface of the operating table and also the platform 2of the supporting structure may be extended at the back such that theoperatingtable when opened can safely rest with its back edge on theplatform 2, in spite of-its weight.

Fig. 3 illustrates theoperation of the described optical system. Lightfrom the lamp I2 'penetrates the'picture film I I and passes undeviatedthrough the rotating octagonal. prism l0 when the incident light isnormal to a face of the prism. The emerging beam is' deviated by theprism I5. According to the position of the latter the beam can be thrownupwards to a collecting lens 3|, and thence reflected by a mirror 32onto a picture screen- 33. Generally, however, the

prism I 5 is so adjusted that the beam is deflected vertically downwardsthrough the lens system I6 and diaphragm disc I1, and is reflected bythe mirror I onto the matt viewing screen 3 which preferably is or iscombined with a field lens as illustrated. In order to permit thetransmission of light in this manner it will be understood, of course,that the successive registration of the slits in the disc II with thelens system I6 will be synchronised with the movement of the faces ofthe prism Ill successively into the position of normal light incidence.Since the rotating prism II) only allows light to pass therethroughundeviated if it is incident normal to the prism surfaces and since allrays deviated by the prism I5 are screened in a sharp manner by theobjective I6 in conjunction with the diaphragm disc Il,.the light beamleaving below the disc I7 is of strong intensity and unbent and alsoundisturbed in any other respect. Consequently, a clear andwell-illuminated picture having sharp edges is projected onto theviewing screen 3.

A bright viewing screen-may be employed instead of a matt screen, as thelatter is not essential, but preferred.

The utility of the apparatus can be enhanced by the provision of meansadapting it for use with films of varying size. A modificationconstructed with this purpose in view is illustrated in Figs. 4 to 8.The layout of the film-feeding devices and the picture and soundpick-ups mounted on the top of the operating table is showndiagrammatically in the plan view of Fig. 4, other details beingomitted. As shown, the arrangement of the lamp and the construction ofthe prism for projecting the picture are a little different from theembodiment shown in Figs. 1 to 3, but this is not material, a similarprojecting arrangement to that previously described may be employed.

Referring now to Fig. 4, light from a projection lamp II 'is collectedby a condenser 42 and projected through the picture film B. The beamthen meets a rotating prism 43 (corresponding to the prism ID of Fig.1), passes through an objective 45 and is projected onto a screen 48.The picture film B and sound film A run together one on the other,coming from the left in the figure,

.over the usual rollers onto the drum 41 Where they part. The picturefilm B runs at the rearward portion of the operating table, over thecustomary rollers, and the sound film A runs similarly at the frontportion. 5| indicates the conventional sound pick-up. The picturev filmruns over a take-up sprocket 53, 54 and the sound film runs overatake-up sprocket 55, 56. The

film feed and take-up spools are of conventional type and'are thereforenot illustrated.

In order to adapt the apparatus for varying sizes of film, the sprocket41 is constructed as a compound or multiple sprocket. Fig. 5 illustratesthe construction for two sizes of film, the sprocket 50 being for usewith standard size film and the sprocket 49 for use with a sub-standardfilm, both sprockets being mounted on the same shaft. Preferably, thesprocket 41 is provided with a number of teeth which will permit aprojection of 16 frames per second.

The prism 43 and objective 45 used with standard film areinterchangeable respectively with a prism 44 and an objective 46 forsub-standard film. Also, the take-up sprockets 53, 54 and 55, 56, areconstructed like the sprocket 41, except that they are of smallerdiameter, the sprockets 53 and 55 taking standard film and thesprookets54 and 56 taking the same sub-standard film as apparatus can be utilizedfor the following film combinations:

(1) Standardpicture film, standard sound film (Fig. 4).

(2) Standard pictur sound film (Fig. 6).

(3) Sub-standard picture film, standard sound film (Fig. '7).

(4) Sub-standard picture film, sound film (Fig. 8).

The figures illustrate the manner in which the picture and sound filmsare passed over the multiple sprockets in each combination. Forconvenience, the standard and sub-standard picture films are indicatedby references B and b respectively and the standard and sub-standardsound films are indicated by A and a respectively.

film, sub-standard sub-standard It is essential that the path of thepicture film from the sprocket 41 to the condenser 42 must be as long asthe path of the soundfilm from the sprocket 41 to the sound pick-up. Thebasic Condition has to be maintained according to Figs. 6 to 8 also whenstandard and sub-standard films are used atthe same time.

As shown in Fig. 4, the centers ofthe prisms 43 and 44 coincide. This isadvantageously obtained by providing that the mount for these objectiveshas the same shaft. The rotating prisms 43 and 44- are interchangeablemost simply by placing them on a rotatable shaft. If the objectives arechanged, then so also must the prisms be changed. The difference betweenthe focal length of the sub-standard film objective 46 and the standardfilm objective 45 can be eliminated by displacing the objective holde'rautomatically, e. .g. by an automatic lever adjustment of known type,when the objective 45 or 46 isinserted, or the arrangement may be madein such a way that the objectives 45 and 46 can only be inserted intothe holder when it assumes the correct position with regard to thepicture screen 48.

An inspection apparatus constructed in such a manner enables a directtransition from substandard film to standard film and vice .versa to bemade without any difficulty. A further advantage of the new apparatus isthat in consequenceof the simplicity of construction, speeds up to 80frames per second can be attained. This speed was only hitherto possiblewith the help of a lens disc which necessitated a rather complicatedoptical arrangement, because otherwise the optical adjustment of theapparatus was damaged.

This application is a division of application, Serial No. 212,784, filedJune 9, 1938.

I claim:

g 1. In a film inspection apparatus comprising means .for projecting animage beam from a constantly moving film, a regular piano-sidedcompensating prism for receiving said image beam and producing astationary image beam, means for directing the image beam emerging fromsaid prism through a shutter to a viewing screen, a common axis for saidprism and shutter, said shutter being adapted to intermittently passonly a limited amount of said image beam, and means for operating andsynchronizing said prism and said shutter to permit only thatportion ofthe image beam which falls at approximately normal incidence to thefaces of said prism to pass said shutter.

2. In a film inspection apparatus comprising means for projecting animage beam from a constantly moving film, a regular plano-sidedcompensating prism for receiving said image beam and producing astationary image beam, means for directing the image beam. emergingfrom'said prism through a shutter to a viewing screen, said shutterhaving a narrow radial slit, a common shaft for said prism and shutterand means for operating and synchronizing the prism and shutter topermit the shutter opening to pass a maximum amount of light when a faceof the prism is normal to the projection axis, said shutter having asufiiciently limited opening to pass only the image beam falling atapproximately normal incidence to the faces of the prism.

3. In a film inspection apparatus comprising means for projecting animage beam from a constantly moving film, a regular plano-sidedcompensating-prism for receiving said image beam and producing astationary image beam, means for focusing and protecting the image beamthrough a shutter to a viewing screen, a common axis for said prism andshutter, and means for operating and synchronizing the prism and shutterso that the shutter opening passes a maximum amount of light when a faceof the prism is normal to the projection axis, said shutter having asufficiently limited opening to pass 4. In a film inspection apparatuscomprising means for projecting an image beam from a constantlymovingfilm, a regular plano-sided compensating prism for receiving said imagebeam and producing a stationary image beam, means for directing theimage beam emerging from said prism through a rotary shutter to a"viewing screen, said shutter having a narrow radial slit,

a common axis for said prism and shutter, and means for operating andsynchronizing the prism and shutter so that the shutter opening passes amaximum amount of light when a. face of the prism is normal'to theprojection axis, said shutter having a sufficiently limited opening topass only the image beam falling at approximately normal incidence tothe faces of the prism.

5. In a film inspection apparatus comprising means for projecting animage beam from a constantly moving film, a regular planosidedcompensating'prism for producing a stationary image from a constantlymoving film, means for directing the image beam emerging from said prismthrough a rotary shutter to a viewing screen, said shutter having aplurality of narrow radial slits corresponding in number to the faces ofsaid prism, and a common shaft for said prism and shutter, said shutterhaving sufiiciently limited openings to pass only the image beam fallingat approximately normal incidence to the faces of.

to the faces oi'the prism, a second reflecting means for directing theimage beam passed by the shutter toa translucent viewing screen, saidviewing screen being'positioned adjacent said source of light, saidviewing screen and two reiiecting means being arranged and adapted toprojectsaid light through a substantially triangular path.

, GUSTAV KEMNA.

